The present invention relates to shunting systems for cerebro-spinal fluid for use in treating hydrocephalus, commonly referred to as "shunting systems", and in particular relates to a catheter for such systems of the type comprising a tube of flexible synthetic polymer, such as silicone rubber, which is provided with a proximal end part for insertion in a cerebral ventricle and/or a distal end part for insertion in a body cavity, the end parts having flow apertures in their respective lateral walls for the flow of cerebro-spinal fluid from the ventricle into the tube and for the outflow of the said fluid from the tube into the body cavity.
The purpose of shunting systems for the treatment of hydrocephalus is to effect periodic drainage of excess cerebro-spinal fluid from the cerebral ventricle, normally ventricle III, in order to maintain the endrocranial tension or pressure at normal physiological values.
Such systems comprise a proximal catheter which consists essentially of a tube which generally runs from the ventricle to the mastoidal region and a proximal or ventricular end part which is inserted in the cerebral ventricle, passing through the foramen of Munro. The other end of this tube, situated in the mastoidal region, is generally connected to the inlet of a capsule, preferably subcutaneous, which acts both as an accumulator-reservoir for collecting the cerebro-spinal fluid drained from the ventricle, and as a pump, operable periodically by a manual compression applied through the skin to exhaust the accumulated fluid downstream.
The outlet of the capsule is connected to one end of a distal catheter consisting of a flexible tube similar to that previously mentioned and extending over a path which is at least partly subcutaneous. The other, distal, end of this latter catheter is inserted into a body cavity to afford a definitive drainage for the fluid. For the present the aforesaid cavity for the discharge of the fluid is the peritoneal cavity, the left cardiac auricle or a jugular vein. In hypersecretive hydrocephalus a shunt for the cerebro-spinal fluid may be provided in the subcutaneous tissue of the nucal region, in the retroperitoneal space, or in a ureter. Other shunting systems comprise a single catheter in the form of a continuous flexible tube which extends from the ventricle to the body cavity into which the fluid is to be discharged.
The catheters are preferably made of flexible silicone rubber tubing but may alternatively be made of other synthetic polymers which are biologically inert. The tubing used may have an internal and external diameter of the order, respectively, of 1.3 millimeters and 2.5 millimeters. The aforesaid capsule, if employed, is preferably of silicone rubber with a reinforcement of "dacron" or polypropylene.
In known shunting systems the aforesaid proximal and distal end parts are formed by the said silicone rubber tubing. These end parts have closed tapered ends and their lateral walls are provided with a multiplicity of small apertures in the form of holes for the ingress of fluid from the ventricle into the internal cavity of the tube or for the discharge of fluid from the internal cavity of the tube into the body cavity.
Shunting systems for hydrocephalus suffer from the severe disadvantage of blockage of the apertures and of the internal bore of the tube, after a certain period of use, frequently less than a year. Such blockage occurs in the proximal and distal end parts as a result of the deposition of filaments of fibrin. These deposits form predominantly on the external surfaces of the end parts.
Such blockages render the shunt system useless and necessitate frequent intervention if severe discomfort for the patient is to be avoided. Furthermore, the surgical intervention, in itself complex, necessary to remove the blockage or replace the shunt system is always attended by risks, and may even be fatal.
These disadvantages are the more acute when it is remembered that the greater part of cases of hydrocephalus occur in very young children and newly born babies.
The primary object of the present invention is to provide a catheter of the type previously referred to which avoids the disadvantages associated with blockage of the apertures and of the bore of the tube in its proximal and/or distal end parts.